DIV. I 



MORPHOLOGY 



145 



All the permanent tissue formed on the inner side of the cambium 

 is termed wood ; this is usually hard and composed of more or less 

 lignified cells. The tissue formed to the outside by the cambium 

 usually consists of unlignified cells and is termed the bast. 





FIG. 168. Transverse section of a stem of Aristolochia Sipho in the tirst year of its growth, showing 

 a vascular bundle with cambium in active division, p, Xylem parenchyma ; vlp, proto- 

 xylem ; m' and m", vessels with bordered pits ; ic, interfascicular cambium in continuation 

 with the fascicular cambium ; v, sieve-tubes ; cbp, protophloem ; pc, pericycle ; sk, inner part 

 of ring of sclerenchymatous fibres. ( x 130. After STRASBURGER.) 



In contrast to the primary cortex all the tissues to the outside of the cambium 

 may be regarded as forming secondary cortex. 



The secondary tissue formed internally by the fascicular cambium 

 resembles the xylem, and that to the outside the phloem of the 

 primary vascular bundle. By the activity of the interfascicular 

 cambium the primary medullary rays are continued through the wood 

 and the bast. Their breadth is, however, usually diminished, since 



L 



